1. Field of the Invention
The present invention relates to efficient pre-conditioning of a substrate, which provides for improved imaging by the sublimation of a dye from a dye carrier device into the surface of a substrate. The present invention imparts and embeds a concentrated colored image, design or pattern from the dye carrier device into the surface of the substrate being imaged. The substrates can include plastics, aluminum, steel, textiles, paperboard, wood, coatings, leather. The imaged substrate has high resolution and may be used, for example, as decorative panels, containers or devices, or as packaging products.
2. Description of the Related Art
Sublimation printing is known in the art. See, for example, U.S. Pat. No. 3,363,557. In carrying out a sublimation printing, a temporary support, such as a carrier or transfer sheet has a sublimable ink and other components applied thereto. Application of the ink can take place by a number of well known techniques such as rotogravure, offset or flexographic printing. The temporary support carrying a sublimable ink composition is brought into contact with the substrate, generally a textile material, although other substrates such as plastics are also known. Heat and pressure are generally supplied which causes the dispersed dyes in the ink to sublimate and migrate from the temporary support into the substrate being processed.
The sublimable inks used in sublimation printing, such as those described in U.S. Pat. No. 3,829,286 are generally known in the art. The inks generally include a dye material, solvent, binders and other conventional ink additives well known to those skilled in the art. Likewise, the use of a temporary support for carrying a sublimable dye, as described in U.S. Pat. Nos. 3,860,388, 3,829,286, 4,576,610 and 4,619,665 is generally known in the art. The temporary support typically includes a flexible support, such as paper, which can resist the heat incurred during the sublimation process. The paper may also include a release layer to prevent ink from permanently adhering to the support. The temporary support is then coated with a sublimable ink in the desired pattern. In some instances a layer of a thermoplastic film or sheet placed between the printed support and the dye receptor (substrate), or a coating may be applied over the sublimable ink, to allow the ink to pass therethrough during the sublimation stage.
U.S. Pat. Nos. 3,860,388, 4,202,663 and 3,994,146 all teach coloration or printing with sublimable dyes, which can include a step of heating before sublimation by the dyes. While such heating before sublimation printing is generally known, as shown by the above patents, the known methods of printing or coloration do not thermally stabilize or increase the surface energy levels of the substrate prior to heated pressured contact of the substrate and temporary support. These methods require higher processing temperatures and increased dwell times, which eliminates use of low temperature stable substrates due to discoloration, melting, or other material failure. These methods also cause sympathetic dye migration, also known in the art as the Venturi or halo effect. This results in a color, design or pattern in the substrate which suffers from long processing times, limited resolution, limited wear resistance, limited color concentration, and limited selection of base plastics able to withstand the heat requirements of the current known processes for sublimation.